As a result of the nonvolatile memory widely used in the electrical devices in recent years, requirements of the nonvolatile memory with high performance have raised, and different types of flash type nonvolatile memory have been developed such as types of floating gate, SONOS, etc. Performances of those memories are affected by manipulation methods of those memories, and the erasing method for nonvolatile memory is very critical to such purpose.
Currently, there are two main techniques about erasing method for flash type nonvolatile memory, which use Fowler-Nordheim tunneling effect and band-to-band hot hole effect. However, one of the mentioned methods, Fowler-Nordheim tunneling effect, needs great erasing voltage and erasing time. In order to decrease the erasing time and the erasing voltage, the thickness of the tunnel oxide should be decreased, but the retention of the memory will deteriorate. The other method by using band-to-band hot hole effect only injects the hot holes to the storage layer near the drain region, but causes the recombination of all electrons in the storage layer, and it will make the threshold voltage of the channel nonuniform and cause the operating characteristic degradation and reliability issues. Therefore, there are problems to be solved in the conventional erase methods for nonvolatile memory.